You have until Friday of the 6th week of classes (please consult the Schedule of Classes calendar for exceptions to this deadline, ie In 2006 Fall quarter the deadline is Thursday of Week 6) to change the grading basis of a class through URSA. After that point, you will need to petition the college for an exception to the Credit Detail rule. Only under extremely rare circumstances are exceptions made to this rule. See Late/Retro Change of Credit Detail.